I saw someone mentioned the word "drone" so I assume that that's what they are. If they're suits that can be remotely operated by Stark using Extremis, it would be even better. And I also hope these armors won't go away at the end of IM3; I want to see them in Avengers 2 and beyond.

I think they're all suits that Stark can control via either the Extremis virus or JARVIS. I tend to believe the rumors that Stark changes his armor in the final battle at least 3 times, meaning that the suits are all functional enough for him to wear.